Biluminal endovascular graft system

ABSTRACT

An endovascular graft system used to repair aneurysms in arteries which bifurcate such as the aorta which bifurcates at the aortoiliac junction. The graft system includes two legs, each defining a lumen. Each leg comprises an aortic stent, a graft component and an iliac stent. The graft component is affixed at one end to the aortic stent and at the other end to the iliac stent. Each leg of the graft system is preferably a mirror image of the other with the exception of the aortic stents. The graft component of each leg includes a means for allowing in situ adjustment of the length of the leg to accommodate the different sizes required for different patients.

This application is a division of U.S. Ser. No. 09/039,776, filed Mar.16, 1998 now U.S. Pat. No. 6,129,756, the content of which is herebyincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to a graft system which is longitudinallyextendible and radially expandable and to an apparatus and a method fordeploying the system across an aneurysm. In particular, this inventionrelates to a biluminal endovascular graft system having two legs, thelength of which can be adjusted in situ to obtain a correct fit for usein excluding an aneurysm.

BACKGROUND OF THE INVENTION

Aortic aneurysms represent a significant medical problem for the generalpopulation. Aneurysms within the aorta presently affect between two andseven percent of the general population and the rate of incidenceappears to be increasing. This form of vascular disease is characterizedby a degradation in the arterial wall in which the wall weakens andballoons outward by thinning. If untreated, the aneurysm can ruptureresulting in death within a short time.

The traditional treatment for patients with an abdominal aortic aneurysmis surgical repair. This is an extensive operation involvingtransperitoneal or retroperitoneal dissection of the aorta andreplacement of the aneurysm with an artificial artery known as aprosthetic graft. This procedure requires exposure of the aorta throughan abdominal incision extending from the lower border from the breastbone down to the pubic bone. The aorta is clamped both above and belowthe aneurysm so that the aneurysm can be opened and the prosthetic graftof approximately the same size as the aorta is sutured in place. Bloodflow is then re-established through the prosthetic graft. The operationrequires a general anesthesia with a breathing tube, extensive intensivecare unit monitoring in the immediate post-operative period along withblood transfusions and stomach and bladder tubes. All of this imposesstress on the cardiovascular system. This is a high-risk surgicalprocedure with well-recognized morbidity and mortality.

More recently, significantly less invasive clinical approaches toaneurysm repair known as endovascular grafting have been proposed. (See,Parodi, J. C., et al. “Transfemoral Intraluminal Graft Implantation forAbdominal Aortic Aneurysms,” 5 Annals of Vascular Surgery, 491 (1991)).Endovascular grafting involves the transluminal placement of aprosthetic arterial graft in the endoluminal position (within the lumenof the artery). By this method, the graft is attached to the internalsurface of an arterial wall by means of attachment devices such asballoon expandable stents, one above the aneurysm and a second below theaneurysm.

Although endovascular grafting represents a desirable improvement overtraditional surgical repair, current endovascular graft systems sufferfrom certain deficiencies. For example, current endovascular graftsystems do not permit in situ adjustment of length. These graft systemsmust either be custom ordered or many different sized grafts must bestocked by the physician in order to accommodate the varying sizes ofdiffering patient anatomies. However, it is difficult to custom order agraft system since a patient's vascular system is three-dimensional andtortuous. Therefore, it is difficult for the physician to obtain anaccurate measurement. Inventorying many different sizes of graft systemspartially solves the problem but is not an acceptable solution becauseif the wrong size is selected the graft system cannot be modified duringthe procedure. Additionally, supplying differing sizes of graft systemscreates inventory problems for the physician.

One method known in the art for overcoming the problem of an incorrectlysized graft is the use of a separate tubular component to extend aportion of the graft system. However, this requires removing the graftdelivery system, opening an additional package with an additionaltubular component, preparing the tubular component for insertion, andreinserting a delivery system to add the tubular component. This addsadditional steps to the procedure and increases the complexity and timerequired to complete the repair. Additionally, current endovasculargraft systems are not designed to allow a single system to treat a widerange of anatomical lengths.

A further problem associated with current endovascular graft systems isthat during deployment the graft system temporarily occludes the aorta,generating a significant downward force. This force makes it difficultto accurately deploy the upper end of the graft system. Such a system isdisclosed in U.S. Pat. No. 5,316,023 issued to Palmaz et al.

Thus, a need exists for an improved endovascular graft system which maybe adjusted in situ to accommodate the varying vascular systems ofdifferent patients without the need to rely on the difficult and ofteninaccurate measurements of the physician. A need also exists for anendovascular graft system which can be deployed in a manner which doesnot occlude the artery, thus enhancing the ability to properly place thedevice.

SUMMARY OF THE INVENTION

This invention provides a graft system and a method for repairing ananeurysm in an abdominal aorta. The aorta branches into two iliacarteries.

In one aspect, this invention is a method for repairing an abdominalaneurysm in an aorta which branches into two iliac arteries with a graftsystem having first and second legs, each leg having a graft componentand an aortic stent attached thereto, comprising: advancing each of thelegs through a separate iliac artery; aligning the aortic stentsrelative to one another in the aorta on one side of the aneurysm, thegraft component of each leg extending into a respective iliac arteryacross the aneurysm; and deploying the aligned aortic stents in theaorta in a manner that does not substantially occlude the aorta. Eachleg may further include an iliac stent. The method then may furthercomprise deploying an iliac stents in a respective iliac artery. Eachleg may have a first end and a second end and the length between thefirst and second ends of at least one of the legs may be adjustable;then the method further comprises adjusting the length of at least oneof the first and second legs by positioning the second end of the leg adesired distance from the first end. At least one of the first andsecond legs may be provided with a bellows region, and then the methodincludes the step of adjusting the length of at least one of the firstand second legs including expanding or contracting the bellows portionof the leg to thereby adjust the length. At least one of the first andsecond legs also may include a first segment and a second segment, thesecond segment being sized to fit within the first segment in atelescoping arrangement; then the step of adjusting further includesadjusting the relative position of the first and second segments suchthat the first end of the leg is a desired distance from the second.

At least one of the first and second legs may include at least onegripping stent; then the method further comprises deploying at least onegripping stent in the bellows region. In addition, at least one of thefirst and second legs may include at least one support stent; then themethod further includes deploying at least one support stent within thesecond segment of the leg to maintain the relative position of the firstand second segments after deployment. The graft system may be providedwith a bellows region and the step of adjusting the length of the graftsystem may include expanding or contracting the bellows portion tothereby adjust the length.

In a second aspect, this invention is a method for repairing anabdominal aneurysm in an aorta which branches into two iliac arterieswith a graft system having first and second ends, comprising: advancingthe graft system through at least one iliac artery; positioning thefirst end of the graft system in the aorta on one side of the aneurysm,the second end of the graft system extending across the aneurysm; anddeploying the first end of the graft system in the aneurysm in a mannerthat does not substantially occlude the aorta. The graft system mayinclude an aortic stent attached to the first end of the graft systemand the step of deploying may include expanding the aortic stentradially outwardly to secure the first end of the graft system in theaorta. The graft system may further include an iliac stent attached tothe second end of the graft system; then the method further comprisesdeploying the iliac stent in the iliac artery. The length between thefirst and second ends may adjustable; then the method further comprisesadjusting the length of the graft system by positioning the second end adesired distance from the first end. The graft system may include afirst segment and a second segment, the second segment being sized tofit within the first segment in a telescoping arrangement; then the stepof adjusting further comprises adjusting the relative position of thefirst and second segments such that the first end of the leg is adesired distance from the second.

In a third aspect, this invention is a method for repairing an abdominalaneurysm with a graft system having first and second legs, each leghaving a graft component with first and second ends, the first leghaving a first aortic stent, the second leg having a second aorticstent, the stents capable of expansion from a first delivery position toa second deployed position, comprising: advancing the first leg throughthe aorta to a desired location on one side of the aneurysm; deployingthe first aortic stent so that it expands to its second deployedposition, the first aortic stent causing the first end of the graftcomponent to maintain a position on a first side of the aorta, the graftcomponent of the first leg extending into a first iliac artery;advancing the second leg through the aorta to a desired locationadjacent the first leg, the graft component of the second leg extendinginto a second iliac artery; and deploying the second aortic stent sothat it expands to its second deployed position causing the first end ofthe second graft component to be positioned adjacent the first end ofthe first graft component on a second side of the aorta. Each legfurther may include an iliac stent attached to the second end of thegraft component; then the method further comprises deploying the iliacstents in a respective iliac artery. The length between the first andsecond ends of at least one of the legs may be adjustable; then themethod further comprises adjusting the length of at least one of thefirst and second legs by positioning the second end of the leg a desireddistance from the first end. At least one of the first and second legsalso may be provided with a bellows region; then the step of adjustingthe length of at least one of the first and second legs may includeexpanding or contracting the bellows portion of the leg to therebyadjust the length. At least one of the first and second legs also mayinclude a first segment and a second segment, the second segment beingsized to fit within the first segment in a telescoping arrangement; thenthe step of adjusting further comprises adjusting the relative positionof the first and second segments such that the first end of the leg is adesired distance from the second.

In a fourth aspect, this invention is a method for placement of abiluminal endovascular graft system having two legs in a vessel of apatient's vascular system, at least one of the legs being adjustable inlength, each leg having first and second attachment elements and a graftcomponent with first and second ends, comprising: providing a singledelivery catheter which contains a first leg of the graft system, theleg being adjustable in length; advancing the delivery catheter to adesired location in the vessel; manipulating the delivery catheter tosecure the first end of the graft component in the vessel with the firstattachment element; manipulating the delivery catheter to adjust thelength of the first leg by positioning the second end of the graft adesired distance from the first end; and securing the second end of thegraft in the vessel with the second attachment element. The first legmay be provided with a bellows region and wherein the step ofmanipulating the delivery catheter to adjust the length of the leg mayinclude expanding or contracting the bellows portion of the leg tothereby adjust the length. The first leg may include a first segment anda second segment, the second segment being sized to fit within the firstsegment in a telescoping arrangement; then the step of manipulating thedelivery catheter to adjust the length of the first leg furthercomprises adjusting the relative position of the first and secondsegments such that the first end of the first leg is a desired distancefrom the second. The first leg may include at least one gripping stent,the method further comprises deploying at least one gripping stent inthe bellows region. The first leg also may include at least one supportstent; then the method further includes deploying at least one supportstent within the second segment of the first leg to maintain therelative position of the first and second segments after deployment.

In a fifth aspect, this invention is a method for repair of an abdominalaortic aneurysm with a graft system having a graft component defining atleast one lumen adapted to extend from the aorta into at least one iliacartery, the graft component having first and second ends, comprising:providing a single delivery catheter which contains the graft system;advancing the delivery catheter to a desired location in the aorta;manipulating the delivery catheter to secure the first end of the graftcomponent on one side of the aneurysm; manipulating the deliverycatheter to adjust the length of the graft component by positioning thesecond end of the graft component on the other side of the aneurysm adesired distance from the first end; and securing the second end of thegraft component in at least one iliac artery. The graft system mayinclude an aortic stent and the step of manipulating the deliverycatheter to secure the first end of the graft component may includeexpanding the aortic stent radially outwardly to secure the first end ofthe graft component in the aorta. The graft system further may includean iliac stent, and the step of securing the second end of the graftcomponent may further comprise deploying the iliac stent radiallyoutwardly to secure the second end of the graft component in the iliacartery. The graft component also may be provided with a bellows regionand the step of adjusting the length of the graft component may includeexpanding or contracting the bellows portion of the graft component tothereby adjust the length. The graft component also may include a firstsegment and a second segment, the second segment being sized to fitwithin the first segment in a telescoping arrangement and the step ofadjusting further comprises adjusting the relative position of the firstand second segments such that the first end of the graft component is adesired distance from the second. The graft system may include at leastone gripping stent; then the method further comprises deploying at leastone gripping stent in the bellows region. The graft system may includeat least one support stent, the method further includes deploying atleast one support stent within the second segment of the graft componentto maintain the relative position of the first and second segments afterdeployment.

In a sixth aspect, this invention is an intraluminal stent capable ofexpanding from a first delivery configuration to a second deployedconfiguration for placement in a vessel of a patient's vascular system,comprising: a first portion having a substantially circularcross-section in the deployed configuration; and a second portionattached to the first portion and having a substantially D-shapedcross-section in the deployed configuration. The second portion may bedefined by a substantially flat alignment surface and a substantiallycurved surface which intersects the alignment surface along two edgesand the attachment of the second portion to the first portion is at afirst point which aligns with one of the edges and a second point whichaligns with the other of the edges.

In a seventh aspect, this invention is a graft system for repairing anabdominal aortic aneurysm comprising a tubular graft component having afirst end portion and a second end portion and a middle portionextending therebetween, wherein the cross-sectional areas of the firstand second end portions is greater than the cross-sectional area of themiddle portion. In addition, an aortic stent may be secured to the firstend portion of the graft component. An iliac stent may be attached tothe second end portion of the graft component. An aortic stent also maybe attached to the first end portion of the graft component and an iliacstent may be attached to the second end portion of the graft component.The tubular graft component further may include a length adjustmentelement. The length adjustment element may comprise a bellows regionwithin the middle portion. The length adjustment element may comprise afirst graft component segment and a second graft component segment, thesecond graft component segment being sized to fit within the first graftcomponent segment in a telescoping arrangement such that the length ofthe graft component can be adjusted by adjusting the relative telescopicposition of the first and second segments. At least one gripping stentmay be adapted to be deployed within the bellows region of the graftcomponent. At least one support stent may be adapted to be deployedwithin the second segment of the graft component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a portion of a human vascular systemdepicting an abdominal aortic aneurysm which extends from below therenal arteries and into the common iliac arteries.

FIG. 2 is a view of the aneurysm of FIG. 1 with the legs of a firstembodiment of the endovascular graft system in their fully deployedpositions with full elongation of the bellows region and the caudal endsnear the internal iliac branches.

FIG. 3 is a view similar to FIG. 2 with the legs of the graft system intheir fully deployed positions with a shortened (compressed) bellowsregion and the caudal ends farther from the internal iliac branches.

FIG. 4 is a cross-sectional view taken along line 4—4 of FIG. 3 showingthe graft system positioned in the aorta, just below the renal arteries.

FIGS. 5 a and 5 b are views of the legs of the embodiment of FIG. 2 inextended and compressed form, respectively, with gripping stents inplace showing the fully deployed shape of the graft system within theaneurysm. FIG. 5 c is a plan view of a gripping stent.

FIGS. 6 a and 6 b are a side view and a top view, respectively, of theD-O stent which comprises the aortic stent of one leg of the embodimentof FIG. 2.

FIGS. 6 c and 6 d are a side view and a top view, respectively, of the Dstent which comprises the aortic stent of a second leg of the embodimentof FIG. 2.

FIGS. 7, 8, 9 a and 9 b are diagrammatic views with portions partiallycut-away and a portion exploded to show the method of delivery anddeployment of one leg of the graft system of FIG. 2 on the right side ofthe aneurysm.

FIG. 10 is a plan view of the legs of a second embodiment of the graftsystem having a focused bellows configuration.

FIGS. 11–13 are diagrammatic views with portions partially cut-away anda portion exploded to show the method of delivery and deployment of oneleg of the embodiment of FIG. 10.

FIG. 14 a illustrates a third embodiment of the adjustable lengthfeature of the graft system showing upper and lower telescoping graftsegments of each leg of the graft system with the graft componentsectioned to illustrate the internal stent structure of this embodiment.

FIG. 14 b shows the embodiment of FIG. 14 a with the graft segmentsoverlapped in a telescoping arrangement.

FIGS. 15–19 are diagrammatic views with portions partially cut-away anda portion exploded to show the method of delivery and deployment of oneleg of the graft system of the embodiment of FIGS. 14 a and 14 b.

FIG. 20 is a cross-sectional view of the delivery system used to insertand deploy the graft system of the embodiment of FIG. 2.

FIGS. 20 a, 20 b, and 20 c are cross-sectional views taken along linesa—a, b—b, and c—c of FIG. 20, respectively.

FIG. 21 is an enlarged cross-sectional view of a portion of the deliverydevice of FIG. 20.

FIG. 22 is an enlarged cross-sectional view of a portion of the deliverydevice of FIG. 20.

FIG. 23 is a cross-sectional view of the delivery system used to insertand deploy the graft system of the embodiment of FIG. 10.

FIGS. 23 a, 23 b, and 23 c are cross-sectional views taken along linesa—a, b—b, and c—c of FIG. 23.

FIG. 24 is an enlarged cross-sectional view of a portion of the deliverysystem of FIG. 23.

FIG. 25 is an enlarged cross-sectional view of a portion of the deliverysystem of FIG. 23.

FIG. 26 is an enlarged cross-sectional view of a portion of the deliverysystem of FIG. 23.

FIG. 27 is a cross-sectional view of the delivery system used to insertand deploy the graft system of the embodiment of FIG. 14.

FIGS. 27 a, 27 b, and 27 c are cross-sectional views taken along linesa—a, b—b, and c—c of FIG. 27.

FIG. 28 is an enlarged cross-sectional view of a portion of the deliverysystem of FIG. 27.

FIG. 29 is an enlarged cross-sectional view of a portion of the deliverysystem of FIG. 27.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The terms “distal” and “proximal” as used in this specification referonly to the delivery device of the graft system, not to the vasculature.The present method contemplates advancement of a catheter in aretrograde manner (i.e., against the flow of blood). Therefore,“proximal” refers to a location closer to the physician and “distal”refers to a location farther from the physician. The vasculature isreferred to with respect to the cranial (closer to head) and caudal(closer to feet) directions. Also, as used in this specification, theterm “above”, in the context of relative positioning with respect to theaneurysm, refers to the region cranial of the aneurysm, for example,within the aorta, whereas “below” refers to the region of thevasculature caudal of the aneurysm, for example, within the common iliacarteries.

Endovascular Graft System

The present invention provides a device and method for treating avariety of abdominal aortic aneurysms. In particular, the graft systemmay be used for treating aneurysms that extend close to or into thecommon iliac arteries. In these aneurysms there is not a suitable placewithin the aorta to seat the lower end of a simple tubular graft.Therefore, the graft must be able to extend into each iliac artery forsuitable seating. By “seating” it is meant that the graft is implanted,fixed, or otherwise attached to the vasculature.

The endovascular graft system of the present invention is a biluminalsystem which may be used to repair aneurysms in arteries which bifurcatesuch as the aorta which bifurcates at the aortoiliac junction. The graftsystem comprises two legs, each defining a lumen. Each leg comprises anaortic stent, a graft component and an iliac stent. The graft componentis affixed at one end to the aortic stent and at the other end to theiliac stent. Each leg of the graft system is preferably a mirror imageof the other with the exception of the aortic stents. As will be seen inthe drawing figures, the aortic stent of the leg oriented in the rightside of the aorta (with respect to the patient) is referred to as a D-Ostent whereas the leg on the left side has an aortic stent which isreferred to as a D stent. Although a particular orientation of the legswithin the aorta is illustrated in the drawing figures it should beunderstood that no particular orientation within the aorta is required,it being necessary only that the graft system be properly positionedwith respect to the renal arteries and iliac arteries as discussed inmore detail hereafter and that the aortic stents be properly alignedwith respect to each other.

Preferably, the graft component of each leg includes a means forallowing in situ adjustment of the length of the leg to accommodate thedifferent sizes required for different patients. This allows for astandard sized graft system (or at least fewer graft sizes) to be usedwhich will accommodate a variety of patients. Thus, the physician is notrequired to inventory multiple sizes nor is the physician required torely on measurements taken of the patients vascular system to select aparticular graft size which may turn out to be incorrect. Severalembodiments of the means for adjusting the length of the legs aredisclosed. These embodiments include what are described as a bellowsconfiguration, a focused bellows configuration and telescoping graftsegment configuration. Each of these configurations is discussed in moredetail hereafter.

FIG. 1 depicts an aneurysm A in the infrarenal aorta and extending intothe common iliac arteries. The infrarenal aorta is that portion of theaorta disposed between the left and right renal arteries RA and thecommon iliac arteries B which branch left and right. Because bilateralsymmetry is shown in the Figures, no distinction is made betweenelements introduced on the left or the right of the patient'svasculature. Each common iliac artery branches into internal andexternal iliac arteries, D and C respectively. External iliac artery Cbecomes the femoral artery below the inguinal ligament. Internal iliacartery D is also known as the hypogastric artery.

FIG. 2 illustrates a first embodiment of the adjustable graft system ofthis invention shown deployed within aortic aneurysm A. O-shaped portion10 of aortic stent 5 of leg 20 may be positioned in neck N of the aortain a manner which overlaps the renal arteries, as shown. Alternatively,the top of O-shaped portion 10 may be positioned just below the renalarteries if the neck N of the aorta is sufficiently long to allow thestent to be securely affixed in that location. Legs 20 and 30 of thebiluminal graft system join together in abutting relationship just belowO-shaped portion 10 to form a circular shape within the lumen of theaorta as will be discussed in more detail hereafter. Bellows regions 25and 35 are adjustable during deployment of legs 20 and 30 and held inplace by gripping stents (not shown) which are described in detailhereafter. Bellows or mid regions 25 and 35 lie between upper aorticstent attachment regions and lower iliac stent attachment regions ofgraft components 40 and 41, respectively. Legs 20 and 30 extend from theaorta into the common iliac arteries B wherein iliac stents 22 and 32,respectively, are affixed to the arterial wall above (i.e., cranial to)the junction of the external and internal iliac arteries, C and D. Thestents may be affixed by means of friction created after the stents haveexpanded radially outwardly, although barbs, hooks, or the like, presenton the stents, are preferred means of attachment. Additionally, thestents and graft components attached to each other, preferably by meansof sutures.

FIG. 3 illustrates the extendible graft system of FIG. 2 deployed withinan aortic aneurysm A which does not extend as extensively into commoniliac arteries B. Thus, iliac stents 22 and 32 are positioned at alocation which is considerably cranial with respect to their position inFIG. 2. As such, bellows regions 25 and 35 are compressed compared tobellows regions 25 and 35 shown in FIG. 2. As in FIG. 2, O-shapedportion 10 of aortic stent 5 is positioned overlapping the renalarteries.

FIG. 4 is a cross-section taken along line 4—4 of FIG. 3. The D-shapedportion 42 of aortic stent 5 of leg 20 is shown aligned with D stent 48of leg 30. D-shaped portion 42 aligns with D stent 48 along alignmentsurfaces 49 and 50. D-shaped portion 42 is surrounded by graft material40 and D stent 48 is surrounded by graft material 41, forming a sealbetween legs 20 and 30 and the aorta.

The generally circular shape formed by the two “D” shapes of the stentsserve to seal off the aneurysm from blood flow, thus directing all bloodflow into the two lumens of the grafts. For an infrarenal aneurysm, theupper end of the graft 40 of each leg may be positioned as close aspossible to the lowest renal artery, as depicted in FIG. 2. Thismaximizes the overlap between graft material and upper aortic neck,assuring a good seal within the artery.

Configuration of Legs of Graft System

The overall configuration of legs 20 and 30 of the embodiment of FIG. 2of the graft system can be best understood with respect to FIGS. 5 a and5 b where the graft components are shown in section to better illustratethe configuration of the stent structure. FIG. 5 a shows legs 20 and 30in a more expanded configuration while FIG. 5 b shows the legs in a lessexpanded configuration. Either of these configurations or modificationsthereof could be used depending on the anatomy of the patient.

Leg 20 includes aortic stent 5 (D-O stent) with O-shaped portion 10 andD-shaped portion 42. D-shaped portion 42 is surrounded by graftcomponent 40 which is fixed to the stent, preferably by sutures. Thegraft material which covers D-shaped portion 42 forms a D-shaped lumen.As the graft component 40 extends away from (below) D-shaped portion 42the graft material tapers inwardly from the aortic region to a midregion or bellows region of graft component 40. The mid region of graftcomponent 40 has a substantially circular cross-section, the diameter ofwhich is preferably uniform. Near the caudal end of the leg the diameterpreferably increases along another transition region to an iliac regionof the graft component which is fixed over the iliac stent 22,preferably by sutures.

One or more gripping stents 46 are positioned between the aortic stent 5and iliac stent 22 to secure the bellows region of the graft componentin place after the length of the leg has been properly adjusted as willbe discussed in more detail hereafter.

The location and configuration of the components of leg 30 are similarto that discussed with respect to leg 20. Specifically, aortic stent 48is affixed to graft component 41, preferably by sutures. A series ofgripping stents 56 is located in a mid region between aortic stent 48and iliac stent 23.

Graft Component

Graft components 40 and 41 of legs 20 and 30 may be made of materialswhich include woven and knitted materials comprising polyester,polytetrafluoroethylene (PTFE), silicones, and urethanes. The materialsmay be porous or nonporous and may be opaque to X-rays. Preferredmaterials include polyester fabric, for example DACRON®, TEFLON®, orother suitable fabric.

A preferred fabric for use in the graft component is a 40 denierpolyester yarn, having 180 to 250 end yarns per inch per face and 80 to120 pick yarns per inch per face. At this weave density, the graftcomponent is relatively impermeable to blood flow through the wall, butyet is relatively thin, ranging between 0.08 and 0.12 mm wall thickness.Preferably, the grafts are woven as tubes with appropriate tapers formeddirectly on the loom. However, desired dimensions for different regionsof the graft component can also be achieved with suture lines orstitching of a flat fabric, or stitching a tubular fabric of an initialuniform perimeter equal to the desired perimeter of the aortic portion.

The graft component of each leg has a generally tubular shape. In afirst embodiment shown in FIGS. 2 and 3, at least a portion of the graftcomponent has a bellows mid region. The bellows or mid region is capableof extending and compressing longitudinally in response to any movementof the ends of the graft component. In a second embodiment discussed inconnection with FIGS. 10–14 the bellows are focused more closely to theaortic portion of the graft component. In a third embodiment discussedlater with respect to FIGS. 14–19 the graft component of each legcomprises at least two tubular overlapping or telescoping segments. Onesegment's diameter may be slightly larger than the other, such that asealing fit is obtained in the overlapping region. All of theseembodiments result in a graft system that allows the physician to adjustthe length of the graft system in situ during the procedure.

In the first and second embodiments the bellows region is formed byplacing the graft component in the fully elongate configuration on amandrel containing a spiral shaped groove. A malleable wire, (e.g.,copper) is wound around the graft, forcing the graft material to conformto the groove in the mandrel. The grooves are smaller than the graftmaterial. The graft material is heat-set in an oven below the meltingtemperature of the graft material. Once removed from the mandrel, thebellows are set allowing the length of the graft component to belongitudinally adjustable during deployment by the physician byadjusting the position of the iliac region of the graft component. Forexample, a polyester graft component with heat set bellows over the fullmid region of the graft component (approximately 12 cm) can elongatefrom about 11 cm in the fully compressed condition to about 20 cm in thefully elongated condition. For simplicity of depiction of the bellows,the graft components shown in, for example, FIGS. 5 a and 5 b show thefull length of the middle region to have a bellows construction.However, only a portion of this region of the graft may have bellows.

The graft material of each graft component is attached to the aorticstent (the upper stent attachment region) and to the iliac stent (thelower stent attachment region) via sutures or other suitable attachmentmeans. Attachment is typically, and preferably, done before the leg ofthe graft system is loaded into the delivery device.

In preferred embodiments, the graft is tapered below the upper stentattachment region. Such is illustrated in FIGS. 5 a and 5 b. Forexample, for an aneurysm neck of 28 mm diameter, the abutting portionsof D stent 48 and D-shaped portion 42 would form a circle as shown inFIG. 4 with a minimum 14 mm minor diameter and at least 28 mm majordiameter. Preferably, the major diameter is sized at least about 2 mmlarger than the diameter of the aneurysm neck in order to insure aproper fit with no leakage and to accommodate either miscalculations inthe size of the aorta or changes in size of the aorta after theprocedure. Over a transition region of about 1 cm, a graft of thisdimension preferably tapers to a uniform diameter ranging from about 8to about 12 mm in the mid region. The graft component then flares up toa uniform diameter of about 12 to 16 mm in the lower stent attachmentregion.

Stents

Numerous stents are employed in the various embodiments of thisinvention. These stents could be self-expanding or expandable via aninternal expanding device such as a balloon. Preferably, the stents areself-expandable and are comprised of a shape memory alloy. Such an alloycan be deformed from an original, heat-stable configuration to a second,heat-unstable configuration. The application of a desired temperaturecauses the alloy to revert to an original heat-stable configuration. Aparticularly preferred shape memory alloy for this application is binarynickel titanium alloy comprising 55.8% Ni by weight. This NiTi alloyundergoes a phase transformation at physiological temperatures. A stentmade of this material is deformable when chilled. Thus, at lowtemperatures (e.g., below 20° C.), the stent is compressed so it can bedelivered to the desired location. The stent is kept at low temperaturesby circulating chilled saline solution. The stent expands when thechilled saline is removed and it is exposed to higher temperatures,e.g., 37° C.

Preferably, the stent is fabricated from a single piece of alloy tubing.The tubing is laser cut, shape-set by placing the tubing on a mandrel,heat-set to its desired expanded shape and size (e.g., D-O shape orD-shape) and electropolished. Electropolishing smoothes the surface ofthe alloy, which is believed to improve fatigue properties as well asextend the strain-to-fracture and also improves thrombogenicityresistance. Preferably, the shape setting is performed at 550° C. forapproximately 20 minutes, followed by aging at 470° C. for 10 minutes.This heat treatment process provides for a stent that has a martensiteto austenite transformation temperature range of less than 15 Celsiusdegrees, and an austenite finish temperature (A_(f)) of slightly lessthan 37° C.

Aortic Stent

As previously discussed, each leg 20 and 30 of the graft system includesan aortic stent. The aortic stents are shown in detail in FIGS. 6 a–6 d.Although discussed in particular with respect to legs 20 and 30 of thefirst embodiment the aortic stents of the other embodiments are similarand this discussion is applicable to those embodiments as well.

Stent 5 of leg 20 consists of an upper O-shaped portion 10 and a lowerD-shaped portion 42. This stent consisting of the upper and lowerportion is also referred to as the D-O stent. Stent 5 includes struts43, shown in FIG. 6 a, which are used to attach the “D”-shaped portion42 of the stent to the “O”-shaped portion 10. It is preferred that onlya few struts are used to effect the attachment, rather than everypossible strut, as this facilitates uniform expansion of the uppercircular portion of the D-O stent during deployment. For example, onlythe two struts at opposite ends of the alignment surface 49 (FIG. 4) maybe attached.

Upper portion 10 of the aortic stent is sized to fit the aorta. Forexample, for a 28 mm aorta, the stent diameter should be about 30 mm.Upper portion 10 is approximately 2 cm in length. It typically isdesirable to “oversize” the stent to assure a good seal and engagementwithin the aorta. A minimum of about 2 mm oversize is preferred. Upperportion 10 is exposed, providing frictional engagement with the aorta.It is also expected that tissue ingrowth occurs faster with an exposedstent, leading to long-term anchoring of the stent. Barbs 45, hooks, orthe like may be used to increase the mechanical fixation of the stent tothe aorta. If barbs 45 are used, they are preferably placed at the lowerend of the o portion of the stent, as shown in FIG. 6 a. Alternatively,the barbs could be located in the D-shaped portion of the stent andproject through the graft to engage the wall of the aorta.

The lower end of D-shaped portion 42 may have a taper to match the taperof the graft (from larger to smaller diameter sections of the graft inthe bellows region).

D stent 48 of leg 30 is substantially D-shaped and has a configurationsimilar to the D-shaped portion 42 of D-O stent 5. This allows stent 48to be aligned with lower portion 42 within the aorta as previouslydiscussed in connection with FIG. 4. Stent 48 may be provided with barbs46 which are provided to further secure the stent to the wall of thevessel, preventing caudal migration of leg 30.

Iliac stents

Iliac stents are attached at the lower end of the graft components, asshown in FIGS. 5 a and 5 b. Similar iliac stents are used in the otherembodiments disclosed herein. Preferably, attachment is via sutures. Thelower end (caudal) of the stent is positioned close to the internaliliac artery without covering the internal iliac artery with the stent.As the internal iliac is a significant vessel, it is desirable to avoidcovering the ostium of the vessel with a stent or graft material.

Typically, the size of the iliac stents ranges from about 12 to about 16mm. The stents may be oversized (i.e., larger than the estimated size ofthe iliac artery by about 2 mm). If they are oversized, excess graftmaterial covering the stent is folded flat between the iliac stent andthe iliac artery after deployment. This is also the case with excessgraft material covering the aortic stents.

The iliac stent may also incorporate barbs, hooks, or the like (notshown) to further secure the iliac stent to the wall of the vessel.

Gripping Stents

Because the bellows region of the graft will tend to elongate whenexposed to internal pressure (e.g., from blood pressure), maintenance ofthe proper length of the graft component is needed during deployment andin situ. Elongation of the bellows is minimized during deployment due tothe presence of the internal delivery catheter and guide wire. Thesecomponents tend to be stiff, preventing significant bowing andelongation of the bellows region, once the bellows have been compressed.

To prevent undesirable lengthening of the graft component once deployed,gripping stents 46 are deployed within the bellows region as seen inFIGS. 5 a and 5 b. These gripping stents, shown in FIG. 5 c, preventelongation of the bellows region due to friction between the graftmaterial and the gripping stents which prevents migration or slipping ofthe graft material after the stent is deployed. Gripping stents 46 maybe provided with barbs 47 at each end to further secure the shortenedbellows region. One or more gripping stents may be used. It is importantthat the full length of the bellows region has gripping stents deployedwithin. In use, if the bellows region has been compressed to arelatively short length only a few gripping stents are necessary tocover the bellows region. If the patient's anatomy requires a longer leglength more gripping stents are required to fully cover the bellowsregion. These gripping stents are deployed immediately following thedeployment of the iliac stent for each leg. Any small “snaking” of thebellows is eliminated once the gripping stents are deployed.

Delivery System and Method of Deployment

Bellows Embodiment

Insertion of each leg of the graft system occurs via the delivery systemshown in FIGS. 20–22. The manner in which the delivery system is usedand the method of deploying the leg 20 of the graft system isillustrated in FIGS. 7–9. The femoral artery is entered within the thighby an arterial incision where the vessel is close to the undersurface ofthe skin. A guide wire is first endoluminally placed, using conventionaltechniques to a position in the patient's thoracic aorta, above anaortic aneurysm such as depicted in FIG. 1. The delivery system of thisinvention is guided into the aneurysm along this guide wire. The guidewire remains in a fixed position throughout the endoluminal procedure.Conventional angiography techniques are employed to identify theaneurysm and the position of key anatomical structures such as the renalarteries.

The delivery system comprises main sheath 120, inner catheter 100, andgripping stent sheath 108. Main sheath 120 covers graft 40 and stents 22(iliac) and 5 (aortic) in compressed configuration. Main sheath 120preferably is formed of thin walled PTFE, having a thickness ofapproximately 0.003 to 0.010 inch, although other polymeric materialssuch as polyethylene or composite structures having a braid or coil mayalso be used. The main sheath diameter is in the range of about 12 to 18French. Handle 102 is connected to inner catheter 100. Inner catheter100 has a central lumen 136 capable of receiving a guide wire 80(typically 0.035 to 0.038 inch diameter stainless steel). Inner catheter100 has a distal end comprising solid bulb 132 which provides a gradualdiameter transition between the guide wire and main sheath 120. Astiffness transition between the relatively flexible guide wire and thestiffer loaded main sheath 120 is provided by bulb 132 as well as bysome length (e.g., 2 cm) of inner catheter projecting distally from bulb132. This stiffness transition allows the loaded delivery system to beadvanced through a tortuous path, often encountered in severe aneurysms.Inner catheter 100 runs through the full length of the delivery system.The aortic stent, the graft component, gripping stents and their sheath,and the iliac stent are mounted about the inner catheter.

Gripping stents 46 are covered by gripping stent sheath 108. At theproximal ends of the gripping stents are individual buttresses 124 whichhelp maintain the position of the gripping stents when the grippingstent sheath is removed.

As best seen in FIG. 22, proximal of the most proximal gripping stent isa “land” area 122 on the gripping stent sheath. In this area the iliacstent 22 is positioned. Further proximal of the iliac stent, thegripping stent sheath becomes dual lumen, the first lumen 138 allowingfor contrast delivery to facilitate location of the internal iliacartery and the second lumen 139 allowing for delivery of saline solutionto cool the stents. The exit port 154 of the contrast lumen residesbetween two wiper seals 160, which transfer the contrast to one of aseries of small holes 156 punched in the side of the main sheath. Duringdelivery, the position of the main sheath relative to the gripping stentsheath and inner catheter will change and, therefore, more than one holein the main sheath is required to assure that an exit is present forcontrast imaging.

Handle 102 is located at the proximal end of the gripping stent sheath108. Handle 102 is connected to inner catheter 100 and permitsmanipulation of inner catheter 100 and movement of the gripping stentsheath relative to the inner catheter. Handle 102 includes a slidingportion 106 connected to the gripping stent sheath. The path that thesliding portion takes is “zigzagged” to permit one gripping stent to bedeployed at a time. Injection ports 112 and 114 are mounted on sliderelement 106. Through these ports are injected radiographic contrastsolution and cold saline, respectively, which flow through the mainsheath. The cold saline may exit from an orifice at the cranial end ofmain sheath 120, and/or from holes 150 in main sheath 120. The coldsaline infusion keeps all of the stents cold until they are deployed.Holes 152 in the gripping sheath beneath the iliac stent keep the iliacstent chilled, and leakage distal to the distal end of the grippingstent sheath and into the distal end of the main sheath keep thegripping stents and the aortic stent chilled until they are deployed.The chilled saline keeps each of the stents in a martensitic phase,minimizing friction between the stents and sheaths for easier sheathretraction during deployment.

Aortic stent 5 and gripping stents 46 are mounted about inner catheter100. Gripping stent sheath 108 holds gripping stents 46 and runs throughthe inside of iliac stent 22 when the system is packaged for delivery.At the distal end of gripping stent sheath 108 there is another buttress125 mounted on inner catheter 100. It abuts gripping stent sheath 108and acts to maintain the position of aortic stent 5 during itsdeployment.

At the proximal end of main sheath 120 is threaded swivel 118. Threadedswivel 118 engages with threads 116 on the outer surface of grippingstent sheath 108. Rotation of threaded swivel 118 controllably withdrawsmain sheath 120 relative to gripping stent sheath 108 and inner catheter100 during deployment of the aortic stents. Careful controlled deliveryof the aortic stent is important to assure its proper final location.This rotation on the threads provides this controlled withdrawal of themain sheath.

One leg of the graft system is positioned by advancing the deliverysystem over the guide wire, deploying the aortic stent, withdrawing themain sheath to expose all but the iliac stent, positioning the iliacstent, deploying the iliac stent, advancing the gripping stent deliverycatheter, and deploying a sufficient number of gripping stents to fullystent the expanded section.

During deployment of the first leg of the graft system, the upperO-shaped portion 10 of the aortic stent serves to position “D”-shapedportion 42 to one side of the aorta, and makes room for the second legto be positioned adjacent the first (i.e., the flat faces or alignmentsurfaces of the D-shape facing each other). O-shaped portion 10 alsoserves to anchor the first leg of the graft system to the aorta. Tofacilitate uniform expansion of the upper O-shaped circular portion ofthe D-O stent during deployment, it is desirable to limit the number ofstruts that are attached between the upper portion and the lowerD-shaped portion. This is shown in greater detail in FIG. 6 a, whichshows struts 43 attaching the upper and lower regions of the stent oneach side. Importantly, during deployment of either leg of the graftsystem, the aorta is never totally occluded. Therefore, there is never astagnation pressure acting on the upper end of either leg duringdeployment. As seen in FIGS. 7–9, during deployment of leg 20, bloodrepresented by arrow 11 can continue to freely flow within the aorta.This facilitates accurately positioning the aortic stents of both legssince no significant pressures are encountered which would tend to forcethe legs in a caudal direction during their deployment.

The deployment of leg 20 of the graft system is illustrated in FIGS.7–9. The delivery system is advanced over the guide wire until theO-shaped portion 10 of aortic stent 5 is in proper position. Typically,the upper edge of the graft material is just below the lowest renalartery. Angiography is used to identify the renal arteries beforedeployment of the aortic stent. One or more radiopaque markers (notshown) positioned along the upper edge of the graft component areattached during manufacture. Additional radiopaque markers are placedalong the upper edge of the alignment surfaces of the graft componentsattached to the D-shaped portion of aortic stent 5 and the D-stent topermit rotational alignment of the legs. To deploy aortic stent 5, innercatheter 100 and gripping stent sheath 108 are grasped via handle 102and their positions maintained while main sheath 120 is withdrawn byturning threaded swivel 118 over threads 116 so that it moves in aproximal direction. Main sheath 120 is further withdrawn until the mainsheath's distal tip is above iliac stent 122. This position isillustrated in FIG. 7, which shows the delivery of the aortic stent 5 atthis stage. In FIG. 7, the iliac stent 22 is still at a point below theinternal iliac branch.

The position of main sheath 120 is maintained while gripping sheath 108,gripping stents 46 and inner catheter 100 are advanced upwards, carryingiliac stent 22 and the iliac end of graft component 40 upward. Graftcomponent 40 extrudes from the end of main sheath 120 causing thebellows in the mid region to compress. In order to properly position theiliac stent above the internal iliac artery, contrast lumen 138 isprovided through gripping stent sheath 108. Holes are provided throughthe gripping stent sheath and the main sheath allowing the contrastfluid to exit the delivery device. When the contrast fluid is detectedby the physician in the internal iliac branch the iliac stent 22 is inproper position. Main sheath 120 is further withdrawn, deploying iliacstent 22 and the lower edge of graft component 40. Part of grippingstent sheath 108, nearest iliac stent 22, serves as a buttress 110 tomaintain the position of iliac stent 22 during withdrawal of main sheath120. FIG. 8 illustrates the deployment of the graft-stent at this finalstage of delivery. Inner catheter 100 and gripping stent sheath 108 arenow moved up (i.e., in the cranial direction).

Leg 20 is now deployed. The bellows region has been compressed orextended as necessary to have the desired graft length. However, thebellows region will tend to elongate. The guide wire, gripping stentsheath 108, and inner catheter 100 will assist in maintaining thecompressed shape of the bellows region during the deployment procedure.In order to permanently fix the shape of the graft component, grippingstents 46 are deployed. These are positioned beginning at the upper endof the bellows region. As gripping stents 46 have been advanced in thecranial direction due to advancement of the iliac stent to its properposition, the gripping stents typically need to be withdrawn to get totheir proper position prior to deployment.

FIG. 9 illustrates the gripping stents and sheath after they have beenmoved caudally. Gripping stents are deployed in sequence by manipulatingsliding portion 106 with respect to handle 102 thus forcing the graftcomponent to take on a relatively straight shape. A sufficient number ofgripping stents are deployed to align the graft component between theaortic and iliac stents. Extra gripping stents not needed are notdeployed and are removed when the delivery device is removed. Thegripping stents thus serve to straighten the bellows region of thegraft, and to prevent them from further elongation after deployment ofthe system. Some space between adjacent gripping stents allows the graftto bend and accommodate any tortuosity within the vascular system. Inthis manner the gripping stents impart kink resistance to the graft.FIG. 9 b shows the fully deployed gripping stents after gripping stentsheath 108 has been fully retracted.

Deployment of the second leg of the system is done in nearly the samemanner as the first leg. The aortic stent 48 of leg 30 is identical tothe lower D-shaped portion 42 of aortic stent 5 of leg 20. In deployingaortic stent 48, a radiopaque marker designating the flat face oralignment surface 50 (FIG. 4) of the stent is rotationally aligned witha similar marker on the alignment surface 49 of the D-shaped portion 42of previously installed D-O stent 5. In this fashion, the flat faces ofthe adjacent aortic stents will properly face each other, assuring aproper orientation of both legs of the system, as illustrated in FIGS.2, 3, and 4.

The second leg of the system is installed in the same manner as thefirst. This includes advancing the system over a pre-advanced guidewire, deploying the aortic stent, withdrawing the main sheath to exposeall but the iliac stent, positioning the iliac stent, deploying theiliac stent, advancing the gripping stent delivery catheter, anddeploying enough gripping stents to fully stent the bellowed portion ofleg 30.

Focused Bellows Embodiment

A second embodiment of the graft system which is a variation on thebellows concept previously discussed is disclosed in FIGS. 10–13. Thestructure of this embodiment is nearly the same as the first embodimentwith the exception of the way the legs are stented in the mid region toachieve a concentration or focusing of the bellows at the upper portionof the mid region. With reference to FIG. 10 the graft system of thisembodiment comprises two legs 320 and 330. Leg 320 includes aortic stent305 having an O-shaped upper portion 310 and a D-shaped lower portion342 which together define a D-O stent which is similar in configurationto aortic stent 5. Graft component 340 is attached to D-shaped portion342, preferably by sutures.

Graft component 340 tapers from an aortic stent region surroundingD-shaped portion 342 down to a mid region having a generally circularcross-section. The sizes of the various components are similar to thosediscussed in connection with leg 20 of the bellows embodiment. Near thecaudal or lower end of the graft component 340 the cross-sectionaldiameter increases along a transition area to an iliac stent attachmentregion which is affixed to iliac stent 322, preferably by sutures.

In the previous bellows embodiment, the graft component was bellowedalong much of the length of the mid region and the subsequently deployedgripping stents fixed the as-adjusted length of the bellows region. Oncedeployed, the bellows of that embodiment are relatively uniformly spreadout along the entire bellows region. In this embodiment, while thebellows are also formed along much of the length of the mid region ofthe graft component, any length adjustment necessary during deploymentserves to “focus” or concentrate the bellows along the upper portion ofthe mid region nearest D-shaped portion 342. In both bellows conceptsthe bellows are fully stretched out when they are within the deliverysystem. This focused region is approximately 4 cm in length. Whendeployed the bellows that were formed in the remaining portion of thegraft component remain fully extended or stretched out.

The concentrated or focused bellows are held in place by a specialmid-stent 350 which is sutured at its upper end at points 351 to thegraft material just below the transition from D-shaped portion 342. Themid-stent 350 is formed of a shape memory alloy as previously described.The lower portion of the stent may have multiple rearward facing prongs352 (i.e., in a cranial direction) which are intended to engage thebellows and fix their position when the stent is deployed. Preferably,these prongs are smooth enough not to fray or puncture the graftmaterial but are strong enough to engage the folds of the bellows toprevent the tendency to elongate caused by internal pressures in thegraft.

Additional support stents 370 are provided between mid-stent 350 andiliac stent 322. These support stents provide radial support to preventkinking or collapse of the graft component.

Leg 330 is similar to leg 320 except that aortic stent 348 is D-shapedto match with the configuration of D-shaped portion 342 of aortic stent305 of leg 320. The relationship of aortic stents 305 and 348 is similarto that discussed with respect to aortic stents 5 and 48 of the bellowsembodiment. Leg 330 further comprises a graft component 341, a mid-stent360 sutured at points 361 to graft components 341 and having prongs 362,support stents 380 and an iliac stent 323, all of which are similar totheir corresponding components of leg 320.

The delivery system for this embodiment is similar to the deliverysystem for the bellows embodiment with some exceptions which will bediscussed below. The delivery system is shown in FIGS. 23–26. Thedelivery system comprises main sheath 420, inner catheter 400, andmid-stent sheath 408. Mid-stent sheath 408 extends distally andterminates such that it covers only the lower or proximal portion of themid-stent. Since in this embodiment, the mid-stent 350 is attached tothe graft component 340 and its position must always stay fixed relativeto aortic stent 305 and the upper end of the graft component, thecatheter/delivery device component that moves the iliac stent intoposition must not move the mid-stent. For this reason, the iliac stentcannot be mounted about the mid-stent sheath. In this embodiment, themid-stent sheath 408 runs beneath the iliac stent, but does not engagethe iliac stent. Thus, the iliac stent can be moved axially along themid-stent sleeve so that it can be positioned properly for deployment. Alumen 439 is formed between inner catheter 400 and mid-stent sheath 408.Lumen 439 provides a path for cold saline.

An iliac stent buttress sleeve 490 runs over the mid-stent sleeve 408and abuts the lower end of iliac stent 322. During iliac stentpositioning the iliac stent buttress sleeve is advanced cranially untilthe iliac stent is in proper position relative to the aneurysm and theinternal iliac branch. The iliac stent buttress sleeve has a lumen, 438which provides a path for contrast fluid. The contrast lumen exitsthrough hole 454 of iliac stent buttress 470 and through holes 450 inthe main sheath.

Handle 402 is connected to inner catheter 400. Inner catheter 400 has acentral lumen 436 capable of receiving a guide wire. Inner catheter 100has a distal end which provides a gradual diameter transition betweenthe guide wire and main sheath 420. Solid bulb 432 forms the cathetertip. A stiffness transition between the relatively flexible guide wireand the stiffer main sheath 420 is provided by bulb 432 as well as bysome length (e.g., 2 cm) of the inner catheter projecting distally frombulb 432. This stiffness transition allows for the loaded deliverysystem to be advanced through a tortuous path, often encountered insevere aneurysms.

Handle 402 permits manipulation of inner catheter 400 and movement ofthe mid-stent sheath relative to the inner catheter. Handle 402 includesa sliding portion 406 connected to the mid-stent sheath 408. The paththat the sliding portion takes is “zigzagged” to permit one supportstent 370 to be deployed at a time. Injection ports 412 and 414 aremounted on handle 402. Through these ports are injected radiographiccontrast solution and cold saline, respectively, which flow through themain sheath. The solutions may exit from an orifice at the cranial endof main sheath 420 and/or from holes 450 in main sheath 420. The coldsaline infusion keeps all of the stents cold until they are deployed.Hole 454 in iliac stent buttress 470 provides a path for a contrastsolution over the iliac stent. The chilled saline keeps each of thestents in a martensitic phase, minimizing friction between the stentsand sheaths for easier sheath retraction during deployment.

At the proximal end of main sheath 420 is threaded swivel 418. Threadedswivel 418 engages with threads 416 on the outer surface of mid-stentsheath 408. Rotation of threaded swivel 418 controllably withdraws mainsheath 420 relative to mid-stent sheath 408 and inner catheter 400during deployment of the aortic and iliac stent.

The first leg 320 of the system with the D-O stent 305 is deliveredfirst, in a manner similar to the previous bellows embodiment.Conventional angiography is used to locate the renal arteries and thedelivery system is advanced over a previously placed guide wire untilthe upper end of the leg 320 is in the desired position relative to therenal arteries. The main sheath is then withdrawn, allowing the D-stentto expand. As in the other embodiments, the O-shaped portion 310 of theaortic stent 5 may be placed across the renal arteries. If the upperneck of the aneurysm is long enough, the entire D-O stent can bepositioned below the renal arteries.

The method of delivery of the graft system can best be understood withreference to FIGS. 11–13. In FIG. 11 aortic stent 305 has been deployedin an appropriate position with O-shaped portion 310 located across therenal arteries. The main sheath 420 is withdrawn until the caudal end ofthe mid-stent 350 has been reached. At this position, a portion ofmid-stent 350 has been expanded. At this point in the deploymentprocedure the iliac stent buttress sheath 490 is advanced craniallyuntil the iliac stent 322 is in a desired position relative to theaneurysm and internal iliac branch (see insert of FIGS. 11 and 12).Contrast injection through the iliac stent buttress sheath facilitatesthis positioning. As the iliac stent is advanced, the bellows of thegraft begin to stack-up over the mid-stent, once the bellows emerge fromthe distal end of the main sheath.

Once the iliac stent is in proper position, the mid-stent sheath 408 isretracted by manipulating sliding portion 406 of handle 402 to fullyexpand the rest of the mid-stent as best seen in FIG. 12. Once themid-stent is fully expanded, the focused bellows are “locked in” by theexpansion of the lower portion of the third stent and its barbs. Thenthe main sheath is withdrawn further until the iliac stent 322 isreleased (FIG. 13). Even though a portion of the graft component belowthe concentrated bellows region was previously formed with bellows,because the graft is loaded in the fully elongated or flattened statethose bellows remains flattened since they did not exit the end of themain sheath during the stage when the bellows were being concentrated.

Once the iliac stent is expanded, the mid-stent sheath 408 is furtherwithdrawn to allow a sufficient number of support stents 370 to expandin the remainder of the graft between the mid-stent and iliac stent. Anyunused support stents are removed with the delivery device.

The second leg 330 of the system with D-shaped aortic stent 348 isdeployed on the contralateral side in the same manner. Markers on ornear the flat side of the D-stent are utilized to orient the D-stent tothe D-shaped portion of aortic stent 305 of leg 320 assuring properdeployment and mating of the flat alignment surfaces of the upper endsof each leg. After that, the procedure for deploying the remainder ofthe stents is the same as described above with respect to leg 320.

Telescoping Leg Embodiment

A third embodiment allowing for in situ adjustment of the legs of thegraft system is shown in FIGS. 14–19. In this embodiment each leg of thegraft system has upper and lower graft segments which fit togethertelescopically to provide longitudinal length adjustment.

FIGS. 14 a and 14 b of the telescoping graft system having legs 570 and575. Leg 570 comprises upper graft segment 566 and lower graft segment568 and leg 575 comprises upper graft segment 576 and lower graftsegment 578. The upper and lower graft segments of each leg are designedsuch that the lower graft segment fits within the upper graft segment ina telescoping arrangement. FIG. 14 b illustrates the legs in theirdeployed and telescoping positions. The positions of the sectionsrelative to one another are maintained by deployment of a plurality ofsupport stents 526.

As best seen in FIGS. 14 a and 14 b, the upper graft segment includes afirst aortic region surrounding the D-shaped portion of the aorticstent. This region may be approximately 2 cm long. The graft componentthen tapers down over a length of approximately 2 cm to a uniformdiameter mid region. This mid region has a diameter of approximately 10mm and a length of approximately 8.25 cm. The lower graft segment has amid region of approximately 10 mm in diameter and 8.25 cm in length. Themid region then flares up from 10 mm to 16 mm over a transition lengthof approximately 0.5 cm. The lower graft segment contains an iliacregion of approximately 16 mm in diameter which is approximately 1 cmlong.

With this configuration, the minimum length of the two overlappedsegments is 13.75 cm, which occurs when both segments' mid regions arefully overlapped. When the segments are installed in their longestconfiguration, approximately 2 cm of the mid regions should overlapyielding a total graft length of approximately 20 cm.

Although this embodiment is shown with two graft segments it will beappreciated that additional segments could be utilized to further extendthe length of the telescoping graft.

The deployment of this graft system is accomplished via the deliverysystem shown in FIGS. 27–29. As in the previous embodiment, the deliverysystem comprises an inner catheter 600 which has a guide wire lumensuitable for passage of a 0.035 or 0.038 inch guide wire. Both the upper566 and lower 568 segments of the legs are loaded into the deliverysystem around inner catheter 600. The upper graft segment is loaded nearthe aortic end (cranial) while the lower graft segment is loaded caudalor towards the iliac end of the delivery system. Preferably, these graftsegments are loaded with no overlap between them. The main sheath 620surrounds these graft segments.

At the distal end of the inner catheter is a flexible bulb 632 whichserves the same purpose as discussed with respect to the otherembodiments. An aortic stent buttress (not shown) is mounted on theinner catheter just proximal of the aortic stent. This buttress servesto keep the aortic stent in position as the main sheath is withdrawnduring deployment. The inner catheter has a secondary bulb 660 locatedjust proximal to the upper graft segment. This bulb serves as a smoothdiameter transition region for the main sheath once the main sheath iscompletely removed from the upper graft segment. This allows for smoothadvancement of the lower graft segment up into the upper graft segmentonce the upper graft segment has been expanded and deployed. The lowergraft segment is positioned just proximal of the secondary bulb.

An iliac stent buttress 610 is mounted about the inner catheter justproximal of the iliac stent (not shown) which is sutured to the proximalend of the lower graft segment. The iliac stent buttress maintains theposition of the iliac stent as the main sheath is withdrawn from thelower graft segment.

The inner catheter has a dual lumen proximal of the iliac stentbuttress. The second lumen 639 provides a path for cold saline infusion.The first lumen 638 is used for contrast delivery to locate the internaliliac branch during iliac stent positioning as described in connectionwith the previous embodiments. Dual wiper or seal rings 662 surround theexit 654 of the contrast lumen to convey contrast from the innercatheter through a hole 656 positioned in the main sheath. In thisembodiment, only a single hole is necessary, as the main sheath will beat a predetermined location relative to the inner catheter and contrastlumen at the time of iliac stent and lower graft segment positioning.

The inner catheter should be long enough proximal to the main sheath toallow for at least 20 cm of withdrawal of the main sheath. The mainsheath of this delivery system is similar to those of the previousembodiments.

In this embodiment, the cold saline infusion is infused between theinner catheter and the main sheath, exiting at the distal end of themain sheath. This results in all stents being chilled prior to theirrelease after withdrawal of the main sheath.

FIGS. 15–19 illustrate the deployment of the telescoping leg embodimentin the human vasculature. FIG. 15 illustrates the placement of thedelivery catheter with distal bulb 632 at the cranial end of the aorta.O-shaped portion 510 is in position and the right leg of the graftsystem is in position. Main sheath 620 is partially retracted and graftcomponent 540 is deploying into its expanded position.

Main sheath 620 is further withdrawn in FIG. 16, showing the upper graftsegment 566 deployed. Since main sheath 620 covers support stents 526its retraction causes them to expand. A plurality of support stents 526are pre-loaded in the delivery catheter. Each is pre-attached to eitherthe upper or lower graft segment depending on its location. In betweenthe support stents there may be support stent buttresses to maintain thecorrect position of the support stents during deployment. The end ofmain sheath 620 is atop secondary bulb 660 which provides a smoothtransition allowing main sheath 620 to be re-advanced smoothly into theupper graft segment.

After deployment of upper graft segment 566, the entire delivery systemis advanced cranially until the iliac stent 522 is in proper positionrelative to the internal iliac artery, as shown in FIG. 17. Injection ofradiographic contrast solution aids in positioning the iliac stent.After positioning of iliac stent 522, main sheath 620 is furtherwithdrawn, allowing the lower graft segment to deploy within the uppersegment as shown in FIG. 18. FIG. 19 shows leg 570 fully deployed andmain sheath 620 being removed through the external iliac artery.

The second leg of the graft system is identical to the first leg exceptwith respect to the aortic stent and is deployed in a similar manneronce the aortic stents are properly aligned with one another in a mannersimilar to that described with respect to the other embodiments.

1. A graft system for repairing an abdominal aortic aneurysm comprisinga one-piece tubular graft component defining a single flow channel andhaving a first end portion, a second end portion, and a middle portionextending therebetween, the first end portion including an aortic stenthaving an O-shaped portion and a D-shaped portion, the middle portionincluding a plurality of independent grasping stents spaced apart fromone another and configured to prevent migration of the graft componentonce deployed, the second end portion including an iliac stent, whereinthe cross-sectional areas of the D-shaped portion of the aortic stentand the iliac stent are greater than the cross-sectional area of themiddle portion and the one-piece graft component tapers from the firstand second end portions to the middle portion.
 2. The graft system ofclaim 1 wherein the tubular graft component further includes a lengthadjustment element.
 3. The graft system of claim 2 wherein the lengthadjustment element comprises a bellows region within the middle portion.